Vinnyl chloride - water

hello, (it was just a mistake when i double-posted dear moderator/administrator, so please let this thread on:uhh: )
how I can calculate the composition of a gas binary mixture of vinyl chloride and water knowing that I have only the following informations:
the water is saturated by the vinyl chloride
the pressure of the mixture is 4bars
or can you tell me what I have to look as information to be able to calculate the concentration of the water in the mixture?

yes it's about a binary gas mixture, but it doesn't depend on the temperature since there are only gases and i just the weight composition.
if you don't know any method to calculate this composition, can you give me any useful website or tables about this??
thank you very much for replying Gokul